1. Field of the Invention
This invention relates in general to filters for heat exchangers. More specifically it relates to a filter for removing corrosive constituents from an air stream which is to be passed in heat exchange relation with a heat exchange coil.
2. Description of the Prior Art
Condensing units for many air conditioning systems are located outdoors where the heat transfer medium used for cooling the refrigerant flowing therethrough is ambient air. A typical outdoor coil assembly includes a vertically extending heat exchange coil and an axial fan having a driving motor mounted perpendicular to, and, at the top end of, the coil. During periods of fan operation, air is drawn in from the outside air to pass through the coil and exits from the unit upwardly through the fan. Typical coil construction comprises what is known as copper tube-aluminum fin coils. Such coils are subject to corrosion when in the presence of an electrolyte. This is due to the position of these materials on the electro-chemical table. Copper is an effective cathode and therefore causes a significant increase in anodic corrosion activity on the aluminum fins.
A large number of air conditioner condensing units are located in environments where an electrolytic solution commonly comes into contact with the copper-aluminum coils. Virtually any coastal, salt water location can experience this problem when mist laden with dissolved salt passes through the condensing coil. The resulting corrosion reduces thermal conduction and air flow causing a decrease in system performance and ultimately failure.
U.S. Pat. No. 1,711,702 "Condenser Assembly" discloses the use of a screen made of metallic wires for removing foreign particles from the flow of air impinging on a condenser heat exchange coil. Such a screen is capable of removing some of the corrosive constituents in an air stream, however a greatly enhanced removal efficiency is deemed desirable to increase the useful life of a condenser coil in a severe corrosive environment.